Gas blast synchronous breaker with gas biased contacts

ABSTRACT

A high power circuit breaker using sulfur hexafluoride as an interrupting medium has a main movable sleeve contact which surrounds an axially movable interrupter contact. The interrupter contact further serves as a valve between high pressure and low pressure SF6 filled regions to permit gas blast through the separating interrupting contacts when the valve is opened. The main movable contact has an extension serving as a downstream shutoff valve which pre-encloses a volume downstream of the interrupter contact prior to the opening of the contacts. The interrupter contact is provided with an extending flange which serves as a short-circuited turn which cooperates with an energizing coil. Energization of the coil repels the shortcircuited turn defined by the flange to initially open the blast valve. High-pressure gas is then applied against the movable contact to move the interrupter contact fully open after the valve is opened. The contacts are synchronously operated so that the contacts open immediately prior to a current zero. The opened contacts are disposed in the high-pressure SF6 region.

United States Patent [191 Mockli June 11, 1974 GAS BLAST SYNCHRONOUS BREAKER WITH GAS BIASED CONTACTS [75] Inventor: Rolf Mockli,Moillesulaz,

Switzerland [73] Assignee: I-T-E Imperial Corporation,

Philadelphia, Pa.

221 Filed: May 26,1972 21] Appl.No.:257,337

3,622.725 ll/l97l McConnell ZOO/I48 B Primary Examiner-Robert S. Macon Attorney, Agent, or Firm0strolenk, Faber, Gerb &

Soffen 5 7 ABSTRACT A high power circuit breaker using sulfur hexafluoride as an interrupting medium has a main movable sleeve contact which surrounds an axially movable interrupter contact. The interrupter contact further serves as a valve between high pressure and low pressure SF 6 filled regions to permit gas blast through the separating interrupting contacts when the valve is opened. The main movable contact has an extension serving as a downstream shutoff valve which pre-encloses a volume downstream of the interrupter contact prior to the opening of the contacts. The interrupter contact is provided with an extending flange which serves as a short-circuited turn which cooperates with an energizing coil. Energization of the coil repels the shortcircuit'ed turn defined by the flange to initially open the blast valve. High-pressure gas is then applied against the movable contact to move the interrupter contact fully open after the valve is opened. The contacts are synchronously operated so that the contacts open immediately prior to a current zero. The opened contacts are disposed in the high-pressure SP region.

27 Claims, 28 Drawing Figures m/apaeza GAP GAS BLAST SYNCHRONOUS BREAKER WITH GAS BI ASED CONTACTS RELATED APPLICATIONS This application is an improvement of copending US. application Ser. No. 823,115, filed May 8, 1969, now US. Pat. No. 3,614,357 in the name of Otto Jensen, entitled GAS BLAST CIRCUIT INTERRUPTER USING MAIN MOVABLE CONTACT AS BLAST VALVE; and is also related to copending US. application Ser. Nos. 256,932, filed May 25, 1972, in the name of Lorne D. McConnell and Rolf Mockli, entitled CO- AXIAL CONDUCTOR CONNECTOR AND GLAND FOR TWO-PRESSURE CIRCUIT BREAKER; 234,893, filed Mar. 15, 1972, in the name of Lorne D. McConnell, entitled INFLATED VALVE SEAT FOR SYNCHRONOUS BREAKERS; and 234,578, filed Mar. 14, 1972, in the name of Lorne D. McConnell, entitled CLOSED CHAMBER WITHIN MOVING CONTACT; all of which are assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates to high power circuit breakers, and more particularly relates'to a novel combination of synchronous interruption techniques with a circuit breaker using sulfur hexafluoride as both an interrupting medium, and a contact drive medium.

Three-phase circuit breakers constructed in accordance with the present'invention, and using synchronous interruption concepts, can be rated at 12,000 amperes at 23 KV and can have an interrupting capability of 150,000 amperes in three cycles. Thus, since each phase will interrupt synchronously, the circuit is fully cleared in three cycles. Moreover, the concepts of the present invention produce high capacity circuit breakers which could be used, for example, for generator protection duty at even higher current ratings than those given above, and at voltage levels up to 34.5 KV. It will be further seen that the breaker of the present invention can be connected in a conventional manner to open bus networks, although the breaker is easily adapted for use directly in isolated phase bus constructrons.

SUMMARY OF THE INVENTION The novel invention incorporates a plurality of individual features in a novel combination. Thus, the interrupter contact consists of a low mass, one-piece moving element which can be opened in less than %s of a millisecond, with opening speeds of over 40 feet per second. This interrupter is operated upon by an electrodynamic drive system which causes the initial movement of the interrupter contact to its open position, which also opens a valve between a high and low-pressure region.

The initial opening of the valve then places the high pressure of the high-pressure region on a relatively large cross-sectional area of the interrupter contact, thereby continuing to accelerate the movable interrupter contact to its open position. Thus, the opening action of the interrupter contact may be appropriately timed by known control circuits, such that opening occurs slightly prior to a current zero in the phase being interrupted.

The construction of the interrupter contact is such that, by itself, it could handle up to, for example, 3,000 amperes continuously while still interrupting up to 150,000 amperes, with considerably less contact erosion than occurs in the contacts of presently available breakers. Moreover, the system issufficiently fast that it could be used as a A cycle breaker in systems up to 34.5 KV. Where higher voltages are involved, plural interrupters may be connected in series,and their operation synchronized with one another.

The interrupting contact is then surrounded by a main movable contact which normally carries substantially the full breaker rated current, which may be up to 12,000 amperes. This main contact is opened in advance of the opening of the interrupter contact, and further serves a downstream cutoff valve by preenclosing a volume downstream of the interrupting contact prior to opening of this contact.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of one installation of a three-phase breaker using the concepts of the present invention.

FIG. 2 is a diagrammatic cross-sectional view of one of the poles of FIG. 1, and is shown to illustrate the controls and housing of the breaker pole.

FIGS. 3a and 3b are detailed cross-sectional views through the interrupting portion of the pole of FIG. 2, and illustrate the details of the construction of the novel breaker of the invention, with the breaker in the open and closed positions, respectively.

FIG. 4 is a plan view of the outer contact ring support of FIGS. 3a and 3b.

FIG. Sis a cross-sectional view of FIG. 4 taken across the section line 5-5 in FIG. 4.

FIG. 6 is a front plan view of the outer contact plate of FIGS. 3a and 3b.

FIG. 7 is a cross-sectional view of FIG. 6 taken across the section line 7-7 in FIG. 6.

FIG. 8 is a front plan view of the outer sealing ring of FIGS. 3a and 3b.

FIG. 9 is a cross-sectional view of FIG. 8 taken across the section line 99 in FIG. 8.

FIG. 10 is a front plan view of one of the spacer plates of FIGS. 3a and 3b.

FIG. 11 is a cross-sectional view of FIG. 10 taken across the section line 11-11 in FIG. 10.

FIG. 12 is a plan view of a support casting for supporting the main movable contact of the breaker of FIGS. 3a and 3b.

FIG. 13 is a cross-sectional view of FIG. 12 taken across the section line 13-l3 in FIG. 12.

FIG. 14 is a plan view of an aluminum casting connected to one of the main aluminum cylinders in FIGS. 30 and 3b.

FIG. 15 is a cross-sectional view of FIG. 14 taken across the section line l515 in FIG. 14.

FIG. 16 is a plan view of a seal retaining ring member used in the device of FIGS. 3a and 3b.

FIG. 17 is a cross-sectional view of FIG. 16 taken across the section line l7-l7 in FIG. 16.

FIG. 18 is a front plan view of the inner piston guide structure of FIGS. 3a and 3b.

FIG. 19 is a cross-sectional view of FIG. 18 taken across the section line 17--I7 in FIG. 18.

FIG. is a cross-sectional view of the seal support ring used for the inflatable seal which cooperates with the movable arcing contact in FIGS. 3a and 3b.

FIG. 20a is an enlarged view of a portion of the seal support of FIG. 20.

FIG. 21 shows the flexible mounted seal support ring of FIG. 20 in FIGS. 3a and 3b.

FIG. 22 is a plan view of the main segmented contact ring of FIGS. 3a and 312.

FIG. 23 is an enlarged view of a few of the contact elements of the contact ring of FIG. 22.

FIG. 24 is a side view of one of the contact elements of FIG. 23.

FIG. shows a cross-sectional view of the coaxial cable connector and gland as connected to the tubular input port of the high-pressure chamber of the circuit breaker of FIGS. 3a and 3b. FIG. 26 is a plan view of the main face of the outer connector section of FIG.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIG. 1, there is schematically illustrated a three-phase, high power circuit breaker intended for use in an open bus system. Thus, the circuit breaker consists of three poles 10, 11 and 12 which are mounted on a platform 13, used in order to bring the poles 10, 11 and 12 up to the height of a particular open bus installation. A control cabinet 14 containing all necessary electrical controls including compressors, gas supply, and the like, is coupled to the individual poles 10, 1 l and 12 through a control conduit 15 in any conventional desired manner. Each of the poles l0, l1 and 12 are carried in their own support housings 16, 17 and 18, respectively, and contain terminal pairs 19-20, 21-22 and 23-24, respectively, which are adapted to connect the bus leading from a generator, for example, to a load circuit.

Each of the poles of FIG. 1 may generally consist of the structure schematically illustrated in FIG. 2 for the case of pole 10. Note that FIG. 2 is intended to show an over-view of the breaker pole and illustrates in linediagram fashion the manner in which electrical and hydraulic controls are connected to the pole. FIGS. and 3b, to be described later, show the detail of the pole contact structure which is only schematically shown in FIG. 2.

Thus, in FIG. 2, the terminals 19 and 20 consist of conductive bus connector terminal members 30-and 31, which have conductive fins 32 and 33 extending therefrom. Terminals 30 and 31 are then connected to end caps 34 and 35, respectively, which are connected to the opposite ends of an elongated insulation housing tube 36. A stationary contact structure 40, to be later described in detail in FIGS. 30 and 3b, is connected to a hollow conductive tube 41, for example, of aluminum, and tube 41 is in turn connected to end cap 34 and terminal 30. A movable, contact structure 42, which cooperates with stationary contact 40, is similarly connected to a hollow conductive tube 43 which is, in turn, connected to end cap 35 and terminal 31.

In addition to the connection of contact structures and 42 to the end caps 34 and 35 by conductive tubes 41 and 43, respectively, heat pipes 44 and 45 are also coupled from the stationary and movable contact structures 40 and 42, respectively, to end caps 34 and 35, respectively, in order to rapidly conduct heat away from the contact structures and from the interior of the breaker. l-Ieat pipes 44 and 45 may be of the wellknown type in which a vaporizable fluid is moved from one end of the pipe to another end by capillary action, thereby to substantially decrease the temperature gradient between the ends of the pipe. Note further that the heat pipes 44 and 45 are disposed centrally and generally along the axis of the breaker pole and do not generally interfere with the assembly or construction of the main breaker components. Note further that heat pipe 44 may extend through an isolating transformer structure 46, which will be described more fully hereinafter.

The elongated insulation tube 36 is provided with integral flanges 47 and 48 which serve to receive clamping members 49 and 50 which allow the clamping of the insulation housing 36 within the main pole housing 16. Further integral flanges 51 and 52 allow the clamping of skirted insulation rings 53 and 54 on the insulation housing 36. Suitable current transformers 55 and 56 may then be mounted on the insulation cylinders 53 and 54, respectively.

As will be seen more fully hereinafter with reference to FIGS. 3a and 3b, the stationary and movable contact structures 40 and 42, respectively, serve as a valve section in a barrier between the right-hand and left-hand portions of the interior of the breaker as well as the breaker contacts. Thus, the left-hand portion of the breaker, that is, to the left of contacts 40 and 42, in general, will be filled with sulfur hexafluoride, for example, under relatively high pressure, for example, 14 to 17 atmospheres (200 to 250 p.s.i.g.). This left-hand high-pressure chamber communicates with conduit 57 in a suitable gas supply system. The right-hand side of the breaker is held at relatively low pressure, for example, 2 to 3 atmospheres of sulfur hexafluoride gas (30 to 45 p.s.i.g.), with the right-hand section of the chamber connected to the gas supply system through conduit 58.

It will be apparent that conduits 57 and 58 will be connected to a suitable compressor and gas'filters in order to maintain the necessary pressure differential between the two chambers.

Once the main contacts are open, a downstream cutoff valve, schematically shown in FIG. 2 as the slide valve 59, closes to cut off volume 59a from the remainder of the low-pressure volume. This volume is proportioned to assure adequate gas flow to effect interruption. This volume remains communicated with the high pressure in the open position. Both contact gaps are thus insulated by high-pressure gas providing high dielectric integrity across the open breaker.

Another important feature of the structure of FIG. 2 is that, once the contacts begin to open, the movable contact is further strongly gas-biased by an initial exposure to the high-pressure system, as will be later described. This feature allows the use of synchronous operating techniques for operating the breaker, whereby the breaker interrupter contacts open just prior to a current zero. Thus, the contacts are subjected to very reduced arcing duty.

The novel synchronous operating mechanism will be described hereinafter in connection with FIGS. 3a and 3b, but the control circuitry is illustrated in FIG. 2. This circuitry includes a suitable synchronous pulse generator 60, shown in block diagram form in FIG. 2, which could take the form shown in US. Pat. No. 3,573,548 in the name of Bachofen, entitled CURRENT ZERO ANTICIPATING DEVICE, and assigned to the assignee of the present invention. Thus, the synchronous pulse generator 60 is suitably coupled to the circuit being protected and connected, for example, at terminals l9 and and generates a pulse output immediately prior to a current zero following some input signal directing that the circuit breaker should be opened. The output of generator is then connected to the control electrode of a triggered spark gap 61 which causes the gap to fire, thereby to allow the discharge of a charged bank of capacitors 62 into the primary winding of an isolating transformer 46.

A novel coaxial connection for carrying the discharge current of capacitors 62 into the interiorly disposed isolating transformer 46 is provided, as will be later described. The secondary winding of the isolating transformer 46 is then connected by a coaxial conductor to an electrodynamic operating system which will be described in connection with FIGS. 3a and 3b, which causes the initial opening of the movable contact at a time just prior to the current zero in the system.

There is also provided, in FIG. 2, a high-speed, threeway gas valve 63 which may be of the type shown in U.S. Pat. No. 3,548,877, and which is operable selectively to connect conduit 64 to high gas pressure, or to low-pressure conduit 65 in order to operate the circuit breaker, as will be later described.

FIGS. 3a and 3b show, in detail, the contact mechanism and support therethrough used in the pole shown in FIG. 2. In FIGS. 3a and 3b, the pole is shown with a center line, with substantially all components being circularly developed around this center line. The breaker contacts are shown in their open position in FIG. 3a and in their closed position in FIG. 3b.

A first main conductive support body contained within the insulation cylinder 36 consists of the outer contact ring support 70. Outer contact ring support is shown separately in FIGS. 4 and 5 so that its outline can be more clearly followed. It will be noted that the support 70 contains a plurality of axially directed openings, such as openings 71 and 72, which surround a central opening 73. In addition, support 70 contains a radial opening 74 which permits high-pressure gas to communicate from the high-pressure conduit 57 through the support 70 and into regions to the left of support 70. The openings, such as openings 71 and 72, permit this high-pressure gas from conduit 57 to pass to the right of support 70.

Support 70 is then bolted to a bolt ring 75 which, in turn, is welded to the right-hand side of conductive cylinder 41. The ring 70 is further tightly fitted within the interior diameter of tube 36, as illustrated.

A reset piston support body is then fitted into the central opening 73 of support 70 and is bolted thereto by suitable bolts, such as bolt 81, shown in FIGS. 3a and 3b. A reclosing piston 82, shown in the open position in FIG. 3a and in its closing position in FIG. 3b, is then fitted within the piston support body 80 with suitable sealing rings disposed between its interior and exterior sliding surfaces.

The reclosing piston 82 has a leftwardly extending flange surface 83 which is supported over an inwardly extending neck 84 of a piston support end cap 85, which is suitably bolted to the reclosing piston support body 80. The body 85 further contains a rubber reset stop ring 86 which receives the left-hand end of neck 83 when the piston 82 is reset in the contact open position of FIG. 3a. The piston 82 further contains a rightwardly extending operating shaft 87, which, as will be seen hereinafter, is used to mechanically close the interrupter contact of the breaker. Note that shaft 87 contains apertures 87a and 87b which are connected to a low-pressure region exterior of shaft 87.

In order to operate the piston 82, a conduit 88, which can be connected to high or low pressure by operation of valve 63, is connected to the right-hand surface of piston 82. A conduit 89 and the left-hand surface of piston 82 are always connected to low pressure.

Thus, conduit 88 is connected, through suitable channels in ring support 70, to the interior of a hollow support rod 90 which is, in turn, connected to input channel 64, which is, in turn, connected to the threeway valve 63, as shown in FIG. 2. In an analogous manner, the conduit 89 is connected through the hollow insulating support rod 91 through other channels which will described hereinafter and ultimately to the input channel 65, which is, again, connected to the three-way valve 63. Accordingly, by suitable operation of the three-way valve 63, channel 88 will be at high pressure or low pressure (and channel 89 remains at low pressure) in order to move the piston 82 to the left, as shown in FIG. 3a. Piston 82 is returned to the position of FIG. 3b by high pressure forces applied during the closing operation, as will be later described.

An outer stationary contact plate 95 is then bolted to the right-hand end of contact support 70. Plate 95 is shown in FIGS. 6 and 7, where it is seen that there are a plurality of bolt pole openings about its periphery for receiving bolts, such as bolts 95a and 95b in FIGS. 3a and 3b for making bolt connection to the support 70. The contact plate 95 defines a radial contact surface 96, which will be seen more fully hereinafter, to slidably receive the main movable contact of the breaker.

Plate 95 further contains channels, such as channels 97 and 98, which are in communication with appropriate openings, such as openings 72 and 71, respectively, in support 70, where the openings, such as openings 97 and 98 in plate 95 allow high-pressure gas from contact 57 to appear to the right of the plate 95.

An impulse coil, which is used in the electrodynamic drive system, is then supported between contact plate 95 and support 80 and is formed of the composite structure including the insulation ring 100, which carries the spirally wound impulse coil winding 101. More specifically, winding 101 may consist, for example, of a spirally wound flat conductor, of for example, 23 turns of flat epoxy coated wire. Filament wound epoxy support rings 102 and 103 are embedded in insulation ring to provide strong mechanical support for the coil 101 and, in a similar manner, an outer filament wound epoxy ring 104 contains the outer diameter of insulation body 100.

The start and finish of winding 101 is then connected to insulated leads, shown partly in dotted lines, as leads 105 and 106, which are taken through suitable openings in insulated body 100. The leads 105 and 106 will be noted\to be coaxial leads as they extend from the isolating transformer 46 of FIG. 2 and remain coaxial until they reach the insulation ring 100. Note that these leads may extend through a suitable opening in the support body 80.

The outer contact plate 95 further carries, at its inner diameter, a contact ring 110 which is conventionally formed of inwardly biased contact segments, where the contact 110 makes sliding contact with the movable arcing contact, to be later described. The contact 110 is held in position on the contact plate 95 by a contact clamping ring and guide 111 which is appropriately bolted to the contact plate 95.

The movable arcing contact 112 is then slidably received on the interior diameter of contact 110. The movable arcing contact 112 is shown in its disengaged position in FIG. 3a and in its engaged position in FIG. 3b, and is formed of a conductive main sleeve body 113 forming an internal cavity and has an inwardly directed flange 114 and an outwardly directed end flange 115. The inwardly directed flange 114 threadably receives an inner arcing electrode extension 114a which has an arcing tip 116. Note that the left-hand end of central member 1 is engageable by the right-hand end of extension 87 of piston 82. The flange 115, as will be described more fully hereinafter, serves as a shorted winding which is closely coupled to impulse winding 101 when the arcing contact is in the closed position. Thus, if the impulse winding 101 is energized while the contact is in the closed position shown in FIG. 3b, extremely high magnetic forces arise, which rapidly move the movable arcing contact 112 to the left.

A buffer 117 is contained in the support body 80 and damps the impact of the movable arcing contact 112 when it reaches its fully open position in FIG. 3a. Further, the pressure differential across contact 112, due to high pressure on its right-hand face and low pressure on its left-hand face, serves to bias the contact in the open position, holding it positively in the full open position and preventing any rebound. The extreme right-hand end of contact 112 then contains an orifice-shaped, inwardly bent arcing contact tip 118, which will be described more fully hereinafter. Note further that the orifice 118 leads to the closed volume or internal cavity formed within the interior of the movable contact 112, thereby to enable gas blast into the interiorof the contact, thereby to allow axial gas flow in two directions, as will be later described.

All of the above-described structure in FIGS. 3a and 3b is generally supported from the main outer contact ring support 70. Spaced from this structure is the structure which carries the main movable contact and the stationary arcing contact, to be more fully described hereinafter. This structure generally includes an outer sealing ring 130 which is fitted within the tube 36 and contains a lower aperture 131 and a central annular depression 132, as further shown in FIGS. 8 and 9.

Sealing ring 130 has a protruding notch 133 extending from the side thereof which nests into an annular notch in the side of spacer plate 134. The spacer plate 134 is spaced from spacer plate 135 which is contained on support 70 and the spacer plates 134 and 135 are held apart by spacer rods including rods 90 and 91.

A plurality of spacer rods, similar to rods 90 and 91, are mounted around the periphery of the spacer plates 134 and 135. By way of example, the spacer plate 135 is shown in FIGS. 10 and 11 and is constructed of aluminum and contains a plurality of openings around the side surface thereof including openings 138 and 139. The facing surface of spacer plate 134 will have similar openings disposed therein, with a plurality of insulation spacer rods, such as rods 90 and 91 being captured between opposing pairs of openings in the spacer plates 134 and 135. The spacer rods themselves may be epoxy glass rods having central channels so that certain of the rods may conduct gas as a part of the gas control system for operating the breaker, as was previously referred to.

The casting 140 is shown by itself in FIGS. 12 and 13 and it will be seen that the casting contains a plurality of L-shaped openings 141 through 146. It will be seen more fully hereinafter that L-shaped openings 141 to 146 are in the channel through which high-pressure gas flows to the low-pressure region during the closing operation. A further L-shaped opening 147 is provided in casting and communicates between conduit 65 and the low-pressure region of the breaker to act as a discharge passage to discharge the high-pressure gas from volume 59a during the closing of the breaker.

The casting 140, as best shown in FIG. 13, further contains a plurality of openings including funnelshaped openings 148 and 149 extending radially through the lefthand end of the member 140. It will be seen that these openings permit control of gas pressure on the main movable contact from conduit 64 when the three-way valve 63 is operated.

The adapter casting then receives, on its lefthand end, a piston stop member 150 which is a simple ring bolted into the left-hand end of adapter 140. The piston stop member 150 carries a sliding seal ring 151 and a rubber stop ring 152.

A ring 160, best shown in FIGS. 14 and 15, is welded to the end of aluminum cylinder 43 and is provided with internal notches 161 to 166. These notches are generally aligned with openings 141 through 146, respectively, in adapter 140 of FIGS. 12 and 13.

A further notch 167 is also provided in member and is in alignment with opening 147 of member 140. Thus, the openings 141 through 147 of member 140 are in communication with the volume within the main low-pressure region within conductive cylinder 43.

For ease of manufacturing, a second ring-shaped member 170, having notched sections in alignment with the notches 161 to 167 of member 160 is clamped between member 160 and the right-hand end of member 140.

A seal retainer ring 171 is then disposed within ring 170 and is bolted to the right-hand end of an inner piston guide casting 172, which will be later described. The right-hand surface of ring 171 has a plate 171a welded thereacross to prevent gas flow through the region in the interior of ring 171. The body of seal retainer 171 is machined from an aluminum casting and contains a series of bolt openings which receive bolts, such as bolts 173 and 174, which are bolted into member 172. Ring 171 then receives a seal retainer insert 175 which consists of an aluminum ring having a plurality of individual channels, such as channels 176 and 177 therethrough.

Each of the individual openings, such as openings 176 and 177 are connected together by an annular channel 178 in one wall of the ring 175. Ring 175 is better illustrated in FIGS. 16 and 17 which more clearly show the channel 178 which joins the openings 176, 177 along with additional openings 179 to 182. It should also be noted that the main ring member 171 contains a passageway therein, shown in FIGS. 3a and 3b as the passageway 190, which communicates with the annular channel 178.

A ring-shaped piston seal member having a generally U shape in section, shown as ring 191 in FIGS. 3a and 3b, is then captured under the seal retainer 175, with the inner periphery of ring 191 being under pressure from member 172 while the outer diameter region of seal 191 is under pressure from the member 147. The seal 191 is of a flexible material, such as rubber, and may be inflated by gas under pressure which is connected beneath the seal by gas admitted to channel 190, and thus into the openings, such as openings 176 and 177 in the seal retainer 175. Thus, the seal 191 may be inflated in order to achieve a good seal relative to the main movable piston member attached to the movable contact independently of seal wear and permanent seal deformation, as will be later described.

The inner piston guide casting 172 is shown in detail in FIGS. 18 and 19 and is held in position from the ring 171, thereby to be supported ultimately from the outer housing 36. It will be noted that a gas conducting conduit 200 is formed in the member 172 with the channel 200 ultimately communicating, to the left of FIG. 3b, to the area immediately adjacent plate 95 including opening 98. Thus, high-pressure gas is applied to the channel 200 so that high-pressure gas is available to in flate the seal 191.

FIGS. 18 and 19 also show the presence of radially directed openings 172a and 1721) (FIG. 19) and further opening 172e in FIG. 3b. These radially directed openings form flow channels for the passage of highpressure gas from the high pressure system during the interruption operation, with this gas continuing to flow through the aligned openings formed on members 170 and 160, described above.

A plurality of bolt openings including opening 201 are formed in member 172 to receive bolts which connect pivot ring 201a in position. Pivot ring 201a supports the flexible contacts of the stationary arcing contact structure, and also has bolted thereto the arcing contact ring 202. Arcing contact ring 202 has connected thereto a central arcing contact body 203. Arcing contact body 203 has an arcing ring tip 204, as shown.

As shown in FIGS. 3a and 3b, the member 172 also carries therein a rubber buffer ring 210, where the buffer ring 210 acts as a shock absorbing stop for the motion of the main piston 211. The main piston 211, which will be described more fully hereinafter, is supported on its exterior by the interior diameter of member 147 and contains a rightwardly extending portion 212 which serves as a downstream cutoff valve in cooperation with the inflatable seal 191. Thus, when the circuit breaker is in the open position of FIG. 3a, the right-hand most end of member 212 is pressed into firm sealing engagement with flexible ring 191 which flexes in order to form a good gas-tight seal with the end of member 212, thereby enclosing the volume 59a of FIGS. 3a and 3b prior to the operation of interrupting contact 112. The main piston 211 is slidably supported by member 147, as previously indicated, with a sliding seal ring 213 disposed between these members, and is also slidably supported relative to member 172 with a sliding seal ring 214 disposed between members 172 and 212. A further sliding seal ring 215 is disposed between ring 150, which also slidably supports the Iefthand outer diameter portion of piston 210.

The outer diameter of the main piston 211 has a contact ring 216 connected thereto which makes sliding contact engagement with surface 96 of contact plate 95. Contact ring 216 is of the segmented contact type, with the individual segments of the ring being spring-biased radially outwardly relative to one another in a manner well known to those skilled in the art. Thus, as shown in FIG. 22, the ring 216 consists of a plurality of individual segments, such as segments 300, 301, 302 and 303. These segments are shown in enlarged fashion in FIG. 23 to illustrate the presence of biasing spring means 304, 305, 306 and 307, respectively. Spring-biasing means 305 has been shown in some detail to illustrate the presence of biasing spring washers 308 and 309 carried on a button spacer 310, such that the fingers 300 and 301 are pressed away from one another. Each of the spring-biased elements will be constructed in this manner for each of the contact elements. Each of the contact elements also have bolt pole openings 315 to 318 and a notch section, shown for the case of finger 300 in FIG. 24 as notch 319.

The individual fingers are then individually and pivotally bolted into the end of main contact piston 211, as shown in FIGS. 3a and 3b, by the bolts 320 and 321 for contact fingers 300 and a further contact finger 322, respectively. Note that the main contact piston 211 contains an inwardly directed protrusion 323 which receives the notches of the contact fingers such as notch 319 of finger 300. This contact operation will be described more fully hereinafter.

The member 172 also receives an inner contact body 220 which is bolted thereto as by bolts 221 and 222 of a ring of bolts disposed circularly around the axis of inner contact body 220. The outer diameter 223 of inner contact body 220 also slidably receives the contact ring 216 attached to the main piston 211. The inner contact body 222 along with body 172 then serves to support the flexible arcing contact structure which cooperates with the movable arcing contact 112.

More specifically, a plurality of finger contacts extend around the interiors of bodies 172 and 220, two of which are shown in FIGS. 3a and 3b as the finger contacts 230 and 231. Typically, 18 such fingers may be disposed in a cylindrical cluster, each mounted in an identical manner between the members 172 and 220. In the case of contact fingers 230 and 231, the righthand ends are captured beneath the flange 232 of member 201a and are pressed against the exterior of flange 232 by biasing springs 233 and 234, respectively.

An intermediate plate 250 and contact guide plate 251 are then bolted to member 220. A flexible seal 252 is wrapped over a seal support ring 253 and is captured between plates 250 and 251. The seal support 253, which may be of brass, and the seal ring 252, are shown in cross-section in FIGS. 20 and 21, respectively, so that their structures can be more clearly understood. Note that plate 251 and plate 250 contain aligned openings, such as openings 260 and 261, respectively, which allow high-pressure gas, to the left of plate 250, to inflate the seal 252 through openings in seal support 253, such as the openings 253a and 253b shown in FIG. 20. Additional openings through the seal support may also be provided around the periphery of ring 253. Each of these openings are joined together by an annular channel 253c in the rear surface of support 253, as clearly shown in FIG. 20 as well as FIG. 20a, which is an enlarged view of channel 2530, where it receives opening 253a. In addition, it will be noted that there is a radial slot 253d leading from channel 253 c and opening 253a to allow communication between opening 253a and the corresponding openings in plates 250 and 251.

The movable arcing contact contains a slightly raised annular protrusion 263 which cooperates with seal 252 by pressing against the seal when the arcing contacts are engaged.

Each of the individual arcing fingers are then provided with arcing tips, such as arcing tips 265 and 266 for arcing contacts 230 and 231, respectively. The ring of arcing contacts on the individual contact fingers then engage the protruding nose terminating in orifice 118 of the contact 112 when the arcing contacts are closed.

It is now possible to consider the operation of the breaker shown in FIGS. 3a and 3b.

CURRENT PATH WHEN BREAKER CONTACTS ARE CLOSED It is first assumed that the breaker contacts are in the closed position, as shown in FIG. 3a. In this closed position, the main contact of the interrupter, consisting of the contact ring 216 carried on main piston 211,- is electrically connected between surface 96 of contact plate 95 and the outer surface of inner contact body 220. The arcing contacts are also engaged where, for example, the extending nose 118 of arcing contact 112 is in engagement with the contact fingers of the stationary arcing contact including contact fingers 230.

The main current carrying path thus consists of a path extending from one terminal of the pole of the breaker, for example, pole 19 in FIG. 2, to the conductive cylinder 41, to adapter 75, to member 70, to contact plate 95 from surface 96 of contact plate 95 into the contact fingers of main contact ring 216, from the other contact surface of the contact fingers of contact 216 into the inner contact member 220, conductive member 172, member 171, member 170, adapter ring 160, conductive tube 43 and thence out to the opposite terminal of the pole, such as terminal 20 of FIG. 2. A small parallel current flow exists through the interrupter or arcing contacts, including arcing contacts 110 and 112.

GAS PRESSURE WITH CONTACTS CLOSED As pointed out previously, sulfur hexafluoride or some other suitable dielectric gas or mixtures thereof at high pressure, is connected to conduit 57 while a relatively low pressure gas is connected to conduit 58. Where SP6 is used as the dielectric medium, conduit 57 might be at about l4 atmospheres, whereas conduit 58 might be at about 3 atmospheres. These two conduits are, of course, suitably connected to an appropriate compressor and filters (not shown) so that the two pressures can be suitably maintained. Similarly, any appropriate monitoring system may be used for monitoring pressures and temperatures of the gas in the breaker and operating the compressor in response to predetermined pressure and temperature conditions.

With the circuit breaker in its closed position, the blast valve formed between protrusion 263 of the interrupting contact 112 and inflated seal 252 is closed. In general, all spaces to the left of this valve in FIGS. 3a and 3b are at high pressure while those regions to the right are at low pressure. Note that the valve is formed immediately adjacent the cooperating interrupting contact surfaces so that, immediately upon interruption operation, gas flow is available to play radially through the arc. It will be further noted that the blast valve is formed between the interrupter contacts and the main contacts (contact ring 216' which bridges between members 95 and 220) so that the main circuit breaker contacts, which need not have interrupting capacity, are disposed in high pressure gas at all times. Thus, the maximum travel of the main movable contact ring 216 is decreased since high voltage can be supported by relatively short distances in SE, under pressure.

The high-pressure gas from conduit 57 fills the region surrounding spacer rods and 91 and the channels, such as channel 74 in member 70 to fill the main highpressure region 400. Note that the isolating transformer of FIG. 2 (not shown in FIGS. 3a and 3b) will be disposed in this high-pressure gas so that the transformer can be made relatively small, since points of relatively high voltage difference can be closer than they normally would be if the transformer was disposed in a lower pressure medium. A further conduit 401 (FIGS. 2 and 3a) is connected into the high-pressure region 400, but this conduit is used to conduct coaxial cable connectors to the isolating transformer and from the discharged capacitors 62 of FIG. 2, and the conduit 401 is normally closed to prevent escape of the highpressure gas from region 400. This same high-pressure gas from conduit 57 appears on the right-hand surface of plate 95 communicating therewith through openings 97 and 98. The high-pressure gas is further prevented from seeping past the outside diameter of main piston 211 by the sliding seal 215.

Low-pressure gas from conduit 58 fills the lowpressure region 402, with this low-pressure extending through the components in members and and then through the openings, such as openings 141 in member 140 and then through the gap to the right of the open end of piston 211 which is not now in sealing engagement with sealing 191 through the openings, such as openings 172a and 172e in member 172 and then up to the valve formed between arcing contact 112 and seal 252.

Low-pressure gas also fills gas passages 89 and 91, which communicate at all times with low-pressure region 402. The volume to the left of member 82 is thus at low pressure, as is the region to the left of arcing contact 112 which communicates with the region within rod 87 through openings 87a and 87b.

Control pressures are also applied through the threeway valve 63 in FIG. 2, such that conduit 88 of FIGS. 3a and 3b is at high pressure, so that the piston 82 is retracted to its left-hand position, as shown in FIG. 3a. Moreover, while the breaker is closed, three-way valve 63 seals off the possible interconnection of conduits 64 and 65.

OPENING OPERATION In order to open the breaker (from the position of FIG. 3b), a trip signal is first derived from some suitable relay source (not shown). This trip signal circuit is schematically illustrated in FIG. 2 as the trip circuit 410. Trip circuit 410 delivers a signal to the three-way valve 63 which is so arranged that, in FIG. 3a, conduit 64 is switched from low pressure (due to its prior connection to conduit 65) to high pressure and sealed off from conduit 65. The switch to high pressure in conduit 64 causes the application of high pressure against surface 412 of piston 211. At the same time, the high pressure against surface 411 of piston 211 is exhausted into low-pressure conduit 65.

Accordingly, the main piston 211 moves rapidly to the right, opening the main contact surfaces and commutating the current through the breaker into the interrupter contacts. At the same time, the high pressure in conduit 64 allows piston 82 to retract to the left, thereby to unblock the interrupter contact 112 and leaving the interrupter contact 112 held in position solely by the contact biasing forces and frictional forces which hold contact 112 in its closed condition.

When pistons 82 and 211 move to the breaker open position, pressure in the operating valve manifold and conduit 64 builds up toward their full high pressure level. When this occurs, in a time of the order of 40 milliseconds, a pressure responsive switch is operated to energize the output circuit of the synchronous pulse generator 60. Output voltage pulses from this generator are then allowed, through suitable control circuitry, to cause the triggering of gap 61 of FIG. 2 and the discharge of capacitors 62 into the isolating transformer 46 and then into the impulse coil 101. Such pulses are delivered in the order of 1.5 milliseconds prior to the next upcoming primary current zero.

The pulse current in the impulse coil 101 then causes a strong electromagnetic repulsive force between coil 101 and the flange 115 of interrupter contact 112, so that the contact 112 begins to move to the left, thereby opening the seal between the circular valve seat 263 on interrupter contact 112 and the inflated valve seal 252. Note that at the time the seal breaks, that the arcing contact 118 and the arcing finger contacts including contacts 230 and 231 are still engaged. With the breaking of the seal, however, high-pressure gas surrounding the interrupter contact now bears against the righthand surface of the interrupter contact contained within valve seat protrusion 263 so that a strong gas pressure force is immediately added to the electrodynamic repulsion force caused by coil 101, thereby rapidly to accelerate the movable contact 112 toward its fully open position.

Once the arcing contacts separate and an arc is drawn, high-pressure gas, which has started to flow through the gap between the separating contacts as soon as the blast valve seal is opened between the seat 263 and seal 252, is immediately available and flowing through the are. It should be noted that this gas flow is in two directions along the axis of the breaker since high-pressure gas can flow into the closed volume of contact 112, which was at low pressure, and can also flow to the right and toward the arcing contact tip 204. This two-directional flow of gas is advantageous in the interruption of the arc. It should also be noted that valve seat 253 is upstream of any arc products produced during blast of gas through the arcs and, therefore, will not be contaminated or subject to burning by the arc.

It will be noted that the specific components are preferably designed such that a gas blast is obtained about 0.5 milliseconds before current zero. This established gas blast will extinguish the current at the next current zero.

Gas flow continues until the closed volume 59a is filled with high pressure SF Note that the separated contacts, including separated interrupter contacts 112 and the contact fingers 230 and 231 are held open in high-pressure gas and so that relatively small gaps can be used to support a relatively high line voltage.

Since the contacts are open just prior to a current zero, the arc energy is extremely limited, so that the breaker will also have excellent dielectric recovery interruption.

The system also employs advantageous mechanicalpneumatic damping structures. Thus, the piston 82 has its end motion damped by engaging the buffer 86. Similarly, the motion of contact 112 is ultimately damped by the bufier 117. Again, the motion of the third moving part-piston 212, is damped by buffer 210. Thus, rubber stops, which may be of any suitable material other than rubber, act to absorb a significant part of the kinetic energy of the moving components. In the case of the buffer 210 for piston 211, it will be noted that even any small recoil of piston 21] will be clamped by the high-pressure gas acting on the surface 412 of the piston, which pressure also positively holds the piston in its contact open and valve sealed condition.

CLOSING OPERATION In order to close the circuit breaker when it is in the open position shown in FIG. 3a, a closing signal is applied to the three-way valve 63, such that conduit 64 is connected to low-pressure conduit 65. Consequently, conduit 88 assumes a low pressure, so that the piston 82 is moved to the right with its extension 87 picking up movable contact 112 to move contact 112 to the right and toward its contact engaged position. At the same time, the pressure on surface 412 of piston 211 is reduced, so that the piston 21] is moved to the left and toward its contact closed position. Note that during this movement to the left, that the downstream cutoff valve formed by the engagement of sleeve 212 and seal 191 is open, thereby exhausting the high-pressure gas to the left of plate 171a and within volume 590, and removing the pressure on the right-hand facing surface of the interrupter contact 112.

The interrupter contact 112 then closes prior to the closing of the main contact 216 carried on piston 211 and the system is then held in the closed position and is prepared for the next opening operation.

INTERNAL CAVITY IN MOVABLE CONTACT In the specific design of interrupter contact 112, to obtain preferred dual axial flow of the high-pressure sulfur hexafluoride gas during interruption, the interior of the closed chamber within the contact should have a volume to permit flow of gas into the chamber during The ability for gas to flow into the enclosed chamber within contact 112 will be controlled to a large measure by the opening size of orifice 118. Thus, the movable contact nozzle opening for orifice 118 could be from 4 inches to inches, which would provide sonic flow capability time periods of from 22.5 milliseconds to 2.5 milliseconds, respectively, for filling the chamber.

In a preferred form of the contact construction, the internal chamber had a diameter of about 2-5/l6ths inches and an axial length of approximately 2 inches. The nozzle opening for the center of orifice 118 was approximately Aaths of an inch. It was found that the use of the closed chamber to produce a dual axial flow of gas during interruption operation increased interrupting performance of the circuit breaker by from to percent as compared to the same form of contact system tested without the auxiliary nozzle added to the movable contact.

COAXIAL CABLE CONNECTION AND GLAND FIGS. 25 and 26 illustrate the structure which connects a coaxial cable from the capacitor bank 62 of FIG. 2 and into the isolation transformer 46 of FIG. 2. Referring to FIG. 25, there is illustrated a coaxial cable 430 which is fastened, for example, to the isolation transformer 46, and which must be taken out through the tubular member 401, to be connected to a coaxial cable section 431 coming from the capacitor bank 62 of FIG. 2. Both coaxial cables 430 and 431 may be identical in construction and consist generally of inner conductors 432 and 433, respectively, and outer conductors 434 and 435, respectively, with the inner and outer conductors spaced from one another by conventional insulation mediums.

FIG. 25 further shows that tubular member 401 terminates in an extending flange 440, which has a circle of bolt openings therethrough including bolt openings 441 and 442. In preparing the coaxial cables 430 and 431 for connection together in the novel connector of FIG. 25, a tubular connector 450 is connected to the interior conductor 432 of cable 430 and is provided with an end surface having an inwardly tapering conical depression. In a similar manner, the central conductor 433 of cable 431 has secured at its end a conical member 451, which has a mating outwardly tapered conical end surface which can make pressure connection with the inwardly tapering surface of connector 450. Both members 450 and 451 are of any suitable conductive material, such as copper.

A plastic sleeve 452, which may be of polytetrafluoroethylene, is formed on the coaxial cable 430 and nests over the adapter head 450 as shown. Moreover, the outer conductor 434 is bent outwardly and over the outer surface of insulation sleeve 452. In a similar manner, an insulation sleeve 453 is formed over the coaxial conductor 431, with member 453 being designated to nest into the end portion of member 452, as shown in FIG. 25.

The outer conductor 435 is'also arranged to extend over the outer surface of member 453. A sealing ring 454 is then placed over insulation member 452, as shown, and a clamping plate 455, which may be of brass, is pressed over the cable 430 and has the outer conductor 434 connected thereto.

A plurality of bolts, including bolts 456 and 457, bolt the member 455 to the adapter 460, thereby applying pressure against the seal 454. The adapter 460 is fitted over the coaxial cable 431 and the plastic sleeves 452 and 453 and compresses rubber gasket 461 against insulation sleeve 453 as shown.

As shown in FIG. 26, the adapter 460 has an enlarged flange 462 which contains a plurality of bolt openings, including bolt openings 463 and 464, which are aligned with the pole openings in flange 440, such as openings 441 and 442, respectively. Note that FIG. 26 also shows the position of threaded openings, such as openings 465 and 466 which receive the bolts 456 and 457, respectively, of FIG. 25.

A plurality of bolts, including bolts 470 and 471, are then used to bolt the flange 462 of member 460 to the flange 440 of member 401, with a sealing ring 472 being compressed between these two bodies.

In the installation of the coaxial connector of FIG. 25, the installer will simply bring the cable 430 with its pre-attached members 455 and 452 slightly out of the tube 401. He will then connect this subassembly to the subassembly including cable 431 with pre-attached members 460 and 453 by bolts such as bolts 456 and 457. This connection will forcibly connect the cooperating conical surfaces of adapters 450 and 451, thereby to make electrical connection between the central conductors 432 and 433. At the same time, the outer conductors 434 and 435 will be connected through the brass bodies of members 455 and 460. Thereafter, the connected members are bolted to the end offlange 440 by bolts, such as bolts 470 and 471.

It will be noted that a complete gas barrier is formed across the end of tube 401 so that the interior of the circuit breaker housing 36 can be safely filled with highpressure gas. Note further that the seals 454 and 461 prevent gas leakage through the individual coaxial cable adapters.

Although this invention has been described with respect to particular embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art and, therefore, the scope of this invention is limited, not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A two-pressure gas blast synchronous circuit interrupter comprising, in combination:

a pressure container having a high-pressure volume and a low-pressure volume, and means for connect ing high-pressure gas and low-pressure gas to said high and low-pressure volumes, respectively;

a main stationary contact and a main movable contact cooperable therewith mounted within said pressure container; said main movable contact consisting of a hollow cylindrical member movable along its axis between an engaged and disengaged position relative to said main stationary contact;

a stationary arcing contact having an orifice therethrough communicable between said high and lowpressure volumes and a movable arcing contact cooperable therewith mounted within said pressure container; said stationary arcing contact comprising an elongated hollow cylindrical member movable along its axis and being coaxial with said main movable contact and disposed internally within said hollow cylindrical member defining said main movable contact;

a blast valve for permitting communication between said high and low-pressure volumes and comprising a circular sealing ring mounted around said orifice in said stationary arcing contact and a cooperating annular sealing means on one end surface of said movable arcing contact which moves into and out of sealing engagement with said circular sealing ring when said movable arcing contact moves to an engaged and disengaged position respectively with respect to said stationary arcing contact; said sta tionary and movable arcing contacts making contact within the interior of said circular sealing ring and said low-pressure volume extending into the interior of said orifice in said stationary arcing contact, whereby, when said movable arcing contact moves to a disengaged position, gas is moved from said highpressure volume and through said arcing contacts and through said orifree;

and impulse coil means stationarily positioned relative to said movable arcing contact and impulse coil cooperating means formed on said movable arcing contact and closely coupled to said impulse coil means when said movable arcing contact is engaged with said stationary arcing contact;

said impulse coil means causing initial movement of said movable arcing contact away from said stationary arcing contact, thereby to open said blast valve; said movable arcing contact having a surface area disposed within said circular sealing ring which is exposed to the high pressure of said highpressure volume immediately upon the opening of said blast valve; I

and circuit means for energizing said impulse coil means only at a given time prior to a zero current magnitude of current through said arcing contacts.

2. The circuit interrupter of claim! which includes operating means for operating said main movable and stationary contact, whereby said main contacts are opened before said arcing contacts are opened and after said arcing contacts are closed.

3. The circuit interrupter of claim 1 which further includes pneumatic operating means for moving said movable arcing contact to a closed position relative to said stationary arcing contact.

4. The circuit interrupter of claim 1 wherein said gas includes sulfur hexafluoride.

5. The circuit interrupter of claim 1 which further includes a downstream cutoff valve for cutting off gas flow through said orifice from said high-pressure volume to said low-pressure volume while said blast valve is opened; said downstream cutoff valve including a circular valve seat which communicates between said orifice and said low-pressure volume, and an end portion of said main movable contact hollow cylindrical member which moves into sealing relation with said circular valve seat when said main movable contact reaches its fully opened position; the open gaps between said areing contacts and main contacts being in the high pressure of said high-pressure volume when said main and arcing contacts are open.

6. The circuit interrupter of claim 1 wherein said movable arcing contact has a radially directed conductive flange at one end thereof defining said impulse coil cooperating means.

7. The circuit interrupter of claim 1 which includes a first stationary support means disposed coaxially with the axis of said movable arcing contact; said first stationary support means containing an annular contact region defining a first portion of said main stationary contact, and containing a centrally disposed sliding contact for slidably supporting said movable arcing contact; and a second stationary support means spaced from said first stationary support means; said second stationary support means supporting said stationary arcing contact and containing an annular contact region defining a second portion of said main stationary contact; said main movable contact being slidably mounted on said second stationary support means and movable in bridging relation between said annular contact regions of said first and second stationary support means.

8. The circuit interrupter of claim 1 wherein said stationary arcing contact includes a plurality of inwardly pressed contact fingers surrounding said orifice.

9. The circuit interrupter of claim 7 which further includes a stationary arcing horn centrally located on said axis of said movable arcing contact and mechanically and electrically connected to said second stationary support means.

10. The circuit interrupter of claim 7 wherein said impulse coil means is mechanically connected to said first stationary support means.

11. The circuit interrupter of claim 1 which includes piston means connected to said main movable contact and pressure connection means for controllably applying pressure to said piston means, thereby to operate said main movable contact.

12. A two-pressure gas blast synchronous circuit interrupter comprising, in combination:

a pressure container having a high-pressure volume and a low-pressure volume, and means for connecting high-pressure gas and low-pressure gas to said high and low-pressure volumes, respectively;

a stationary contact having an orifice therethrough communicable between said high and low-pressure volumes and a movable contact cooperable therewith mounted within said pressure container; said stationary contact comprising an elongated hollow cylindrical member movable along its axis; blast valve for permitting communication between said high and low-pressure volumes and comprising a circular sealing ring mounted around said orifice in said stationary contact and a cooperating annular sealing means on one end surface of said movable contact which moves into and out of sealing engagement with said circular sealing ring when said movable contact moves to an engaged and disengaged position respectively with respect to said stationary contact; said stationary and movable contacts making contact within the interior of said circular sealing ring and said low-pressure volume extending into the interior of said orifice in said stationary contact whereby, when said movable contact moves to a disengaged position, gas is moved from said high-pressure volume and through said contacts and through said orifice; and impulse coil means stationarily positioned relative to said movable contact and impulse coil cooperating means formed on said movable contact and closely coupled to said impulse coil means when said movable contact is engaged with said stationary contact;

said impulse coil means causing initial movement of said movable contact away from said stationary contact, thereby to open said blast valve; said movable contact having a surface area disposed within said circular sealing ring which is exposed to the high pressure of said high-pressure volume immediately upon the opening of said blast valve;

and circuit means for energizing said impulse coil means only at a given time prior to a zero current magnitude of current through said contacts.

13. The circuit interrupter of claim 12 which further includes pneumatic operating means connected to said movable contact for moving said movable contact to a closed position relative to said stationary contact.

14. The circuit interrupter of claim 12 which further includes a downstream cutoff valve for cutting off gas flow through said orifice from said high-pressure volume to said low-pressure volume while said blast valve is opened.

15. The circuit interrupter of claim 12 wherein said movable contact includes an integral conductive flange formed as a short-circuited turn, thereby to define said impulse coil cooperating means.

16. The circuit interrupter of claim 12 which further includes an isolation transformer for transmitting an impulse signal from an external source to said impulse coil means; said isolation transformer being mounted within said high-pressure volume.

17. A high-voltage circuit interrupter using a combination of gas blast interruption techniques and synchronous circuit interruption techniques andincluding a gas pressure assisted opening operation comprising:

an orifice-shaped stationary contact and a movable contact movable with respect thereto between an engaged and disengaged position;

a gas-pressure barrier between a high-pressure region and low-pressure region; said stationary contact being mounted in said barrier and defining an orifice therethrough; said movable contact defining a movable valve for sealing the periphery of said orifice when said contacts are in their said engaged position;

said movable contact being disposed on the highpressure side of said barrier whereby, as soon as said movable contact moves away from said stationary contact and toward said disengaged position, high-pressure gas presses against a surface of said movable contact previously connected to lowpressure gas, thereby to accelerate the opening movement of said movable contact;

and an electrodynamic drive system for causing the initial movement of said movable contact to its disengaged position; said electrodynamic drive system including first impulse coil means connected to said movable contact and second impulse coil means stationarily mounted relative to said movable contact and closely coupled to said first impulse coil means when said movable contact is in its said engaged position; and impulse circuit means connected to said second impulse coil means to apply a pulse current thereto when it is desired to open said circuit interrupter.

18. The high-voltage circuit interrupter of claim 17 wherein said impulse circuit meansincludes zero current anticipation means and applies a pulse current to said second impulse coil means at a given time prior to a current zero in the current flowing through said circuit interrupter.

19. The circuit interrupter of claim 18 which further includes pneumatic means connected to said movable contact for moving said movable contact from said disengaged position toward said engaged position.

20. The circuit interrupter of claim 18 which further includes a downstream cutoff valve for cutting off gas flow from said high-pressure region to said lowpressure region after current flow between said movable and stationary contacts is interrupted.

21. The device of claim 1 wherein said main movable contact includes a contact ring formed-of a plurality of contact segments; each of said contact segments containing respective biasing spring means; each of said contact segments making sliding contact on an elongated cylindrical surface of said main stationary contact; said biasing spring means exerting a contact pressure between their respective segments and said elongated cylindrical surface.

22. The circuit interrupter of claim 21 which includes operating means for operating said main movable and stationary contacts, whereby said main contacts are opened before said arcing contacts are opened and after said arcing contacts are closed.

23. The circuit interrupter of claim 22 which further includes pneumatic operating means for moving said movable arcing contact to a closed position relative to said stationary arcing contact.

24. The circuit interrupter of claim 21 which includes a first stationary support means disposed coaxially with the axis of said movable arcing contact; said first stationary support means containing an annular contact region defining a first portion of said main stationary contact, and containing a centrally disposed sliding contact for slidably supporting said movable arcing contact; and a second stationary support means spaced from said first stationary support means; said second stationary support means supporting said stationary arcing contact and containing an annular contact region defining a second portion of said main stationary contact; said main movable contact being slidably mounted on said second stationary support means and movable in bridging relation between said annular contact regions of said first and second stationary support means.

25. The circuit interrupter of claim 7 which further includes first and second elongated conductive hollow cylinders within and concentric with said pressure container and being respectively connected at one end to said first and second stationary support means and each extending away from one another and insulated from one another; first and second main terminals disposed externally of and at opposite ends of said pressure container; said first and second elongated conductive cylinders being electrically connected at their opposite ends to said first and second main terminals.

26. The circuit interrupter of claim 25 which further includes first and second heat pipe means respectively connected in thermal conducting relation to said first and second stationary support means respectively and to said first and second main terminals.

27. The circuit interrupter of claim 7 which further includes first and second main terminals disposed externally of and at opposite ends of said pressure container and respectively connected to said first and second stationary support means respectively; and first and second heat pipe means respectively connected in thermal conducting relation to said first and second stationary support means respectively and to said first and second main terminals. 

1. A two-pressure gas blast synchronous circuit interrupter comprising, in combination: a pressure container having a high-pressure volume and a lowpressure volume, and means for connecting high-pressure gas and low-pressure gas to said high and low-pressure volumes, respectively; a main stationary contact and a main movable contact cooperable therewith mounted within said pressure container; said main movable contact consisting of a hollow cylindrical member movable along its axis between an engaged and disengaged position relative to said main stationary contact; a stationary arcing contact having an orifice therethrough communicable between said high and low-pressure volumes and a Movable arcing contact cooperable therewith mounted within said pressure container; said stationary arcing contact comprising an elongated hollow cylindrical member movable along its axis and being coaxial with said main movable contact and disposed internally within said hollow cylindrical member defining said main movable contact; a blast valve for permitting communication between said high and low-pressure volumes and comprising a circular sealing ring mounted around said orifice in said stationary arcing contact and a cooperating annular sealing means on one end surface of said movable arcing contact which moves into and out of sealing engagement with said circular sealing ring when said movable arcing contact moves to an engaged and disengaged position respectively with respect to said stationary arcing contact; said stationary and movable arcing contacts making contact within the interior of said circular sealing ring and said lowpressure volume extending into the interior of said orifice in said stationary arcing contact, whereby, when said movable arcing contact moves to a disengaged position, gas is moved from said high-pressure volume and through said arcing contacts and through said orifice; and impulse coil means stationarily positioned relative to said movable arcing contact and impulse coil cooperating means formed on said movable arcing contact and closely coupled to said impulse coil means when said movable arcing contact is engaged with said stationary arcing contact; said impulse coil means causing initial movement of said movable arcing contact away from said stationary arcing contact, thereby to open said blast valve; said movable arcing contact having a surface area disposed within said circular sealing ring which is exposed to the high pressure of said highpressure volume immediately upon the opening of said blast valve; and circuit means for energizing said impulse coil means only at a given time prior to a zero current magnitude of current through said arcing contacts.
 2. The circuit interrupter of claim 1 which includes operating means for operating said main movable and stationary contact, whereby said main contacts are opened before said arcing contacts are opened and after said arcing contacts are closed.
 3. The circuit interrupter of claim 1 which further includes pneumatic operating means for moving said movable arcing contact to a closed position relative to said stationary arcing contact.
 4. The circuit interrupter of claim 1 wherein said gas includes sulfur hexafluoride.
 5. The circuit interrupter of claim 1 which further includes a downstream cutoff valve for cutting off gas flow through said orifice from said high-pressure volume to said low-pressure volume while said blast valve is opened; said downstream cutoff valve including a circular valve seat which communicates between said orifice and said low-pressure volume, and an end portion of said main movable contact hollow cylindrical member which moves into sealing relation with said circular valve seat when said main movable contact reaches its fully opened position; the open gaps between said arcing contacts and main contacts being in the high pressure of said high-pressure volume when said main and arcing contacts are open.
 6. The circuit interrupter of claim 1 wherein said movable arcing contact has a radially directed conductive flange at one end thereof defining said impulse coil cooperating means.
 7. The circuit interrupter of claim 1 which includes a first stationary support means disposed coaxially with the axis of said movable arcing contact; said first stationary support means containing an annular contact region defining a first portion of said main stationary contact, and containing a centrally disposed sliding contact for slidably supporting said movable arcing contact; and a second stationary support means spaced from said first stationary support means; said second stationary support means supporting said stationary arcing contact and contaiNing an annular contact region defining a second portion of said main stationary contact; said main movable contact being slidably mounted on said second stationary support means and movable in bridging relation between said annular contact regions of said first and second stationary support means.
 8. The circuit interrupter of claim 1 wherein said stationary arcing contact includes a plurality of inwardly pressed contact fingers surrounding said orifice.
 9. The circuit interrupter of claim 7 which further includes a stationary arcing horn centrally located on said axis of said movable arcing contact and mechanically and electrically connected to said second stationary support means.
 10. The circuit interrupter of claim 7 wherein said impulse coil means is mechanically connected to said first stationary support means.
 11. The circuit interrupter of claim 1 which includes piston means connected to said main movable contact and pressure connection means for controllably applying pressure to said piston means, thereby to operate said main movable contact.
 12. A two-pressure gas blast synchronous circuit interrupter comprising, in combination: a pressure container having a high-pressure volume and a low-pressure volume, and means for connecting high-pressure gas and low-pressure gas to said high and low-pressure volumes, respectively; a stationary contact having an orifice therethrough communicable between said high and low-pressure volumes and a movable contact cooperable therewith mounted within said pressure container; said stationary contact comprising an elongated hollow cylindrical member movable along its axis; a blast valve for permitting communication between said high and low-pressure volumes and comprising a circular sealing ring mounted around said orifice in said stationary contact and a cooperating annular sealing means on one end surface of said movable contact which moves into and out of sealing engagement with said circular sealing ring when said movable contact moves to an engaged and disengaged position respectively with respect to said stationary contact; said stationary and movable contacts making contact within the interior of said circular sealing ring and said low-pressure volume extending into the interior of said orifice in said stationary contact whereby, when said movable contact moves to a disengaged position, gas is moved from said high-pressure volume and through said contacts and through said orifice; and impulse coil means stationarily positioned relative to said movable contact and impulse coil cooperating means formed on said movable contact and closely coupled to said impulse coil means when said movable contact is engaged with said stationary contact; said impulse coil means causing initial movement of said movable contact away from said stationary contact, thereby to open said blast valve; said movable contact having a surface area disposed within said circular sealing ring which is exposed to the high pressure of said high-pressure volume immediately upon the opening of said blast valve; and circuit means for energizing said impulse coil means only at a given time prior to a zero current magnitude of current through said contacts.
 13. The circuit interrupter of claim 12 which further includes pneumatic operating means connected to said movable contact for moving said movable contact to a closed position relative to said stationary contact.
 14. The circuit interrupter of claim 12 which further includes a downstream cutoff valve for cutting off gas flow through said orifice from said high-pressure volume to said low-pressure volume while said blast valve is opened.
 15. The circuit interrupter of claim 12 wherein said movable contact includes an integral conductive flange formed as a short-circuited turn, thereby to define said impulse coil cooperating means.
 16. The circuit interrupter of claim 12 which further includes an isolation transformer for transmitting an impulse signal from an external source to said impulse coil means; said isolation transformer being mounted within said high-pressure volume.
 17. A high-voltage circuit interrupter using a combination of gas blast interruption techniques and synchronous circuit interruption techniques and including a gas pressure assisted opening operation comprising: an orifice-shaped stationary contact and a movable contact movable with respect thereto between an engaged and disengaged position; a gas-pressure barrier between a high-pressure region and low-pressure region; said stationary contact being mounted in said barrier and defining an orifice therethrough; said movable contact defining a movable valve for sealing the periphery of said orifice when said contacts are in their said engaged position; said movable contact being disposed on the high-pressure side of said barrier whereby, as soon as said movable contact moves away from said stationary contact and toward said disengaged position, high-pressure gas presses against a surface of said movable contact previously connected to low-pressure gas, thereby to accelerate the opening movement of said movable contact; and an electrodynamic drive system for causing the initial movement of said movable contact to its disengaged position; said electrodynamic drive system including first impulse coil means connected to said movable contact and second impulse coil means stationarily mounted relative to said movable contact and closely coupled to said first impulse coil means when said movable contact is in its said engaged position; and impulse circuit means connected to said second impulse coil means to apply a pulse current thereto when it is desired to open said circuit interrupter.
 18. The high-voltage circuit interrupter of claim 17 wherein said impulse circuit means includes zero current anticipation means and applies a pulse current to said second impulse coil means at a given time prior to a current zero in the current flowing through said circuit interrupter.
 19. The circuit interrupter of claim 18 which further includes pneumatic means connected to said movable contact for moving said movable contact from said disengaged position toward said engaged position.
 20. The circuit interrupter of claim 18 which further includes a downstream cutoff valve for cutting off gas flow from said high-pressure region to said low-pressure region after current flow between said movable and stationary contacts is interrupted.
 21. The device of claim 1 wherein said main movable contact includes a contact ring formed of a plurality of contact segments; each of said contact segments containing respective biasing spring means; each of said contact segments making sliding contact on an elongated cylindrical surface of said main stationary contact; said biasing spring means exerting a contact pressure between their respective segments and said elongated cylindrical surface.
 22. The circuit interrupter of claim 21 which includes operating means for operating said main movable and stationary contacts, whereby said main contacts are opened before said arcing contacts are opened and after said arcing contacts are closed.
 23. The circuit interrupter of claim 22 which further includes pneumatic operating means for moving said movable arcing contact to a closed position relative to said stationary arcing contact.
 24. The circuit interrupter of claim 21 which includes a first stationary support means disposed coaxially with the axis of said movable arcing contact; said first stationary support means containing an annular contact region defining a first portion of said main stationary contact, and containing a centrally disposed sliding contact for slidably supporting said movable arcing contact; and a second stationary support means spaced from said first stationary support means; said second stationary support means supporting said stationary arcing contact and containing an annular contact region defining a second portion of said main stationary coNtact; said main movable contact being slidably mounted on said second stationary support means and movable in bridging relation between said annular contact regions of said first and second stationary support means.
 25. The circuit interrupter of claim 7 which further includes first and second elongated conductive hollow cylinders within and concentric with said pressure container and being respectively connected at one end to said first and second stationary support means and each extending away from one another and insulated from one another; first and second main terminals disposed externally of and at opposite ends of said pressure container; said first and second elongated conductive cylinders being electrically connected at their opposite ends to said first and second main terminals.
 26. The circuit interrupter of claim 25 which further includes first and second heat pipe means respectively connected in thermal conducting relation to said first and second stationary support means respectively and to said first and second main terminals.
 27. The circuit interrupter of claim 7 which further includes first and second main terminals disposed externally of and at opposite ends of said pressure container and respectively connected to said first and second stationary support means respectively; and first and second heat pipe means respectively connected in thermal conducting relation to said first and second stationary support means respectively and to said first and second main terminals. 